Clock thermostat apparatus for controlling the temperature in a space at a normal controlled temperature during certain periods of time and reducing the controlled temperature to a lower temperature for heating and a higher temperature for cooling or during other selected periods of time for energy conservation are broadly old. An early thermostat of this type is shown in the Carl G. Kronmiller U.S. Pat. No. 2,558,617 which issued June 26, 1951. Over the years many other clock thermostats have been developed, both mechanical or electrical time mechanism, such as the thermostat disclosed in the Arlon D. Kompelien application, Ser. No. 639,523, filed Dec. 10, 1975, as well as a more complicated electronic thermostat as disclosed in the John M. Whitney U.S. Pat. No. 4,248,375, issued Feb. 3, 1981. Thermostats of this type have been placed on sale by the applicants' assignee in the form of the T8084A Dial Set Chronotherm Thermostat, the T8082A Chronotherm Fuel Saver Thermostat, and the T800A Microelectronic Fuel Saver Thermostat. With the advent of a more concentrated effort for energy saving, the market for a less expensive minimal feature energy saving thermostat has greatly increased.
The present invention is concerned with a minimal feature energy saving thermostat which provides an electronic temperature sensing and control circuit to maintain the temperature during a first period of time with a means to reset the control temperature to an energy saving temperature during a second period of time. The second period of time is manually settable in the thermostat by a time interval counter means which provides electrical pulses to a visual indication device and to a storage means for storing a number of pulses indicative of time intervals as the pulses are visually counted for the energy saving temperature period of time. By means of a review switch, the stored pulses can be reviewed by the visual indication device to determine the energy saving temperature time period.